A study has linked plasma levels of proneurotensin with the development of diabetes, cardiovascular disease, cardiovascular and total mortality, and breast cancer in women. Neurotensin, an amino acid peptide primarily expressed in the central nervous system and gastrointestinal tract, regulates both satiety and breast cancer growth in the experimental setting, but little is known about its role in the development of breast cancer or cardiometabolic disease in humans, according to researchers. Proneurotensin is a precursor of the hormone neurotensin.